A digital plant protection system of a nuclear power plant disclosed in Patent Literature 1 has been known as a control system for a nuclear power facility. The digital plant protection system includes a main control room, a remote shutdown panel, and an apparatus control system processor. The main control room is connected to the apparatus control system processor, and it is possible to operate an apparatus of an emergency response system provided in the nuclear power plant by transmitting a signal from the main control room to the apparatus control system processor. In addition, the remote shutdown panel is connected to the apparatus control system processor, and it is possible to manually operate an apparatus of an emergency response system provided in the nuclear power plant by transmitting a signal from the remote shutdown panel to the apparatus control system processor when an operator may not stay in the main control room. Then, the operated apparatus of the emergency response system carries out an emergency response such as a shutdown of a nuclear reactor and the like.
Incidentally, an apparatus provided in a nuclear power facility is divided into a safety protection apparatus and a normal apparatus (non-safety protection apparatus). The safety protection apparatus is an apparatus that operates the nuclear power facility to a safety mode when an abnormality occurs, and the normal apparatus is an apparatus that controls the nuclear power facility during a normal operation. When the safety protection apparatus is a digital apparatus, it is assumed that a defect such as a common cause failure occurs in the safety protection apparatus. For this reason, the nuclear power facility is provided with a CCF apparatus by assuming an occurrence of a common cause failure of the safety protection apparatus. The CCF apparatus is operated as a normal apparatus. In this instance, the safety protection apparatus is designed so that operation guarantee increases in proportion to the CCF apparatus which is a normal apparatus. For this reason, it is needed to be configured such that a signal output from the safety protection apparatus is prior to a signal output from the normal apparatus so that the signal output from the safety protection apparatus is not inhibited by a signal output from the CCF apparatus in regulation.
Herein, for example, when an apparatus provided in a main control room is the safety protection apparatus, and a remote shutdown panel is the CCF apparatus in a conventional digital plant protection system, a signal output from the safety protection apparatus and a signal output from the CCF apparatus are transmitted to an apparatus control system processor. In this instance, there is a concern that the signal output from the safety protection apparatus may be inhibited by the signal output from the CCF apparatus.
Hence, an object of the invention is to provide a control system for a nuclear power facility capable of operating an apparatus provided in the nuclear power facility to a safety mode without inhibiting a signal output from a safety main control device even when a signal is output from a normal auxiliary control device.